Mounting brackets designed to facilitate the installation of luminaires and other office furniture components to vertical walls and modular office panels are well known. However, it is also known that tolerances in the fabrication of luminaires, mounting brackets, modular file cabinets, and modular office panel systems can result in panel-mounted and cabinet-mounted luminaire installations that are out of level in profile. This out of level profiling may also occur in the case of wall mounted luminaires due to surface variations where the luminaire mounting brackets are installed. Often the result occurs with the forward or unsupported edge of the luminaire positioned below that of the rear edge (though the opposite can also occur). This resulting “sag” disadvantageously reduces the shielding angle of the ambient lighting and may disadvantageously affect the distribution of light on tasks below the luminaire, where task or task/ambient luminaires are used. Thus, a convenient means for leveling a luminaire attached to a surface via a bracket system would be desirable.